Janet conducts a study on social loafing (letting other group members do most of the work). Similar to a prior research study she read about, she alters whether the student participant is alone or in a group. However, she adds a new dimension: whether the students in the group know or do not know each other. She finds that students by themselves worked harder than students in groups. In addition, she found that social loafing is lessened if the students in the group know each other as opposed to if they are strangers. Janet's study represents a. a replication study.b. a replication with extension study.c. lack of control.d. a synthetic study.